Separation of Ir, Pd and Rh from secondary Pt scrap by precipitation and calcination

Secondary platinum scrap from the glass industry with iridium, rhodium and palladium additions arising from alloys or enrichment due to multiple recycling of the construction elements was used to study the refining behavior and to define and control parameters influencing the selectivity and yield. Dissolving this material in boiling aqua regia, diluting with water or hydrochloric acid and precipitating with ammonium chloride (NH4Cl), then separating the mother liquor gives a precipitate, where the accompanying platinum group metals (PGMs) iridium, rhodium and palladium are separated from the platinum matrix. Calcination of the precipitate gives a sponge of high purity (>99.90%). The influence of the dilution of the solution with water and/or hydrochloric acid, as well as the temperature of the precipitation, has been investigated.